# Relationship history for MSHA mine 2901819

Current hierarchy: **Herrera Robert → B & J Sand & Gravel → B&J SAND & GRAVEL**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Del-Valley Corp → B&J SAND & GRAVEL; 1980-04-01 to 1986-05-04; source msha-controller-operator-history
- **controller_controls_mine:** Wallace D W → B&J SAND & GRAVEL; 1980-04-01 to 1986-05-04; source msha-controller-operator-history
- **controller_controls_operator:** Wallace D W → Del-Valley Corp; 1980-04-01 to 1986-05-04; source msha-controller-operator-history
- **operator_operates_mine:** B & J Sand & Gravel → B&J SAND & GRAVEL; 1986-05-05 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Herrera Robert → B&J SAND & GRAVEL; 1986-05-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Herrera Robert → B & J Sand & Gravel; 1986-05-05 to current/open; source msha-controller-operator-history